Does anyone know of any good sites/reports on graduate employability???

Have you tried UKGrad website at http://www.grad.ac.uk ? I remember seeing statistics, they might have reports too.

You could try prospects.ac.uk & run a search on graduate employability.
They some times have useful links to national surveys & stuff.

Thanks x

Your best bet are the HESA Destination statistics which you can download from www.hesa.ac.uk

These are the people who send you a questionnaire six months after graduation to ask what you are up to.